This invention relates to solar power systems, and, more particularly, to a solar power source having a solar concentrator, and to an approach for improving the performance of the solar concentrator and thence the solar power system.
A solar power system has a solar power converter that converts incident light energy into power. One type of solar power system includes a solar panel, which is a photovoltaic device that converts the incident light energy into electrical power. Such solar power systems are used on many types of spacecraft to provide a replenishable source of power. For example, most geosynchronous communications satellites use solar power systems to produce the power needed to amplify received signals for re-transmission back to earth.
Solar panels typically include a solar cell, which is a semiconductor material that achieves the conversion of light energy into electrical current. The output power of the solar cell increases with the intensity of the incident light, and it is therefore desirable to increase the incident intensity above that associated with normal incident sunlight. Such an increase may be accomplished with a lens, but a lens is too heavy to be practical for spacecraft applications.
Another approach to increasing the intensity of the incident light is to use a solar concentrator, which is a reflective panel positioned adjacent to the solar panel to reflect incident light toward the solar panel. The intensity of the light incident upon the solar panel is therefore up to several times that of the normal intensity of sunlight. The concentrator is much lighter in weight than the solar panel, so that a greater incident energy of sunlight is effectively utilized for generating electrical power without a comparable increase in weight.
Existing solar concentrators improve the performance of solar power systems substantially. However, the present inventor has recognized that limitations in fabrication technology prevent the existing solar concentrators from achieving their potential performance. A conventional solar concentrator for spacecraft applications comprises a thin layer or sheet of plastic material with an overlying layer of a reflective metal such as aluminum. Defects in the reflective layer, such as wrinkles, holes, or deposition defects, can produce shadows on the solar panel, concentrate the incident sunlight as hot spots in some regions, scatter the incident sunlight, or otherwise interfere with the light field incident upon the solar panel. The result is an uneven distribution of light intensity across the face of the solar panel, which adversely affects its performance. It is difficult to avoid such problems even with careful attention to the fabrication of the solar concentrator, inasmuch as its area is quite large.
There is, accordingly, a need for an improved solar concentrator for use in solar power systems. The present invention fulfills this need, and further provides related advantages.